This invention relates to rotary machinery bearings and, more specifically, relates to tilting shoe pad bearings.
In the design of high speed rotary machines, one of the most significant problems is the adjustment of shaft bearings in response to vibrations and uneven loading. With an inflexible journal bearing, even a small displacement of the bearing can cause severe uneven loading and consequential damage. Furthermore, heavy vibrations are transmitted through the bearing to the supporting structure.
Therefore, it is desirable to minimize the effects of vibration and uneven loading. If flexibility is provided so that some transverse motion of the journal bearing is permitted, the undesirable forces can be reduced. The rocking action of the shoes of the existing tilting pad journal bearings provides a degree of transverse motion and adjustment to help alleviate the problem.
Various types of tilting pad bearings have now been proposed including bearings having arcuate shoes held in place by radial pins which are loose fitting to permit rocking of the shoes. Another arrangement makes use of the pin point contact of a ball upon a flat surface in combination with mechanical stops such as the arrangement shown in U.S. Pat. No. 3,887,245 issued to Rouch in 1975.
Although the existing tilting pad bearings are effective in somewhat reducing the problems associated with rotary shaft misalignments and vibrations, none of these provide a simple arrangement wherein the bearing shoes may be free floating but yet are provided with universal adjustability and support, about one point, forces from all of the radial, circumferential and axial directions.
It would therefore be advantageous if a tilting pad bearing were provided which were uniquely uncomplicated but yet would provide universal adjustability.